Autobiography of William Joseph Dibdin F.I.C., F.C.S.
Analytical Chemist
1850 - 1925

THE PURIFICATION OF THE THAMES

TREATMENT OF SEWAGE

The serious condition of the River which occurred during the dry season of 1884 immediately called for drastic action with the result that the Metropolitan Board of Works instructed Sir Joseph Bazalgette and myself to report as to the best means of permanently curing the evil and to make any experiments which we considered necessary to elucidate all the facts.  As a preliminary we decided to carry out a series of trials at the Pimlico Pumping Station, in Grosvenor Road, and experimental works were installed there, the quantity of sewage first dealt with being one thousand gallons, increased as information was gained, to 100,000 gallons by utilising the River water settling ponds already there.  The results of these experiments were described by me in my evidence before Lord Bramwell’s Royal Commission later on.  The success of our work was such that the Board decided to extend them at the Crossness Pumping Station, below Woolwich, where a plant was put up for treating one million gallons daily in order to obtain sufficient sludge to experiment with to ascertain the best way of disposing of it with the least nuisance and expense.  Portions were pressed to obtain it in the form of semi-solid “cakes,” in which state it was claimed that it would be suitable for use as a manure, and consignments were sent free of expense to farmers, Manure manufacturers, and some to brick burning kilns to see how it could be burnt, whilst other quantities were used to fill up low-lying land.  The net result was that it was found that the best way would be to “manure” our fish fields by discharging it into the Estuary of the Thames by carrying out to the Barrow Deep, ten miles below the Nore, in specially constructed barges and there discharging it into the water below the surface over a ten mile course, and his was finally adopted and is continued to the present time.  The technical details of this work were summarised in a paper read by me before the Institute of Civic Engineers in 1894, which was a sequel to me I read there in 1887 on what we proposed to do, for which I was awarded a Telford Premium.

Although thus shortly summarised the work extended over ten years before the process was fully at work, during which time numerous investigations were made in connection with various proposed alternative processes, and almost weekly reports on these were made to the Board by the Engineer and myself.

One of the first ideas tried at the Pimlico experiments was to ascertain how far the process of aerating the sewage by blowing air through it in various ways would affect purification.  These were correct in the chemical theory so far as supplying oxygen was concerned but it soon became evident that another factor, viz; time and Biology must be taken into account as the immediate effect of aeration was very limited and until the water organisms which feed upon the sewage matters had time to develop and exert their useful function of eating up the matters little result accrued from an excess of air.  All this however is fully described in my book on “The purification of sewage and water” and need not be more fully referred to here.

In order to follow the varying conditions of the River both in regard to its action condition and the quantity of deodorising chemicals required, as described in the previous chapter, I made weekly trips on the River from London to the Outfalls at Barking and Crossness and occasionally to the Estuary, a special boat being place at my disposal for the purpose.  On board we carried out chemical tests of the water of the River as we went along, thus securing definite information in addition to that gained at the two Outfall Laboratories where my assistants made daily analyses of the River water at both High and Low tide as well as samples of the sewage, effluents and general stores and chemicals used for the treatment of the sewage.  It was in connection with this work that an interesting fact was ascertained which had a bearing on the other branch of my work as Superintending Gas Examiner to the Council.  In order to ensure the supply of Lime of good quality for the treatment of the sewage, of which material we required about twenty thousand tons per annum, I had instituted a specification which required that the lime must be up to a certain standard.  When a barge load came up to the Wharf it was examined and if good accepted, but if not rejected.  It had often been a matter of surprise that the barge man in charge did not seem to mind whether we took it or not but went off quite happily.  On one occasion the South Metropolitan Gas Co had a good deal of trouble with the Sulphur purifying plant and appealed to the Chief Gas Examiner, Dr Williamson, to disallow the report of the Gas Examiner as to an excess of Sulphur.  At the Inquiry the Gas Company stated that they had exhausted all their efforts and that the excess of Sulphur was due to “an unavoidable cause or accident,” and asked the Chief Gas Examiner to inspect their works to satisfy himself as to the correctness of their statement.  The Doctor did not seem to relish the job and asked me if I would go.  I accordingly went, although strictly it was not part of my official duties.  The first thing I asked about when I arrived at the works was as to the lime and on examining this I found it to be, roughly, half burnt chalk.  I then asked them where they got it from when I was not surprised to hear that it was from a lime burner whose deliveries to our Outfalls had to be frequently refused.  I put the Company up to the trick.  Gave them a copy of the specification and, as they afterwards informed me, saved them two thousand a year!  An amusing sequel to this occurred sometime afterwards when I was giving evidence before a Committee of the House of Commons on a Gas Bill, when Balfour Brown, Counsel for the Gas Company, asked me in cross examination “But you are not a Gas Engineer?”  When I replied that my experience was such that on one occasion I had been able to show the Company how to save £2000 per annum, where upon George Livesey, the Chairman of the South Metropolitan Gas Company, who was standing behind Balfour Brown, called out “Ah; but that was a chemical question.”  As if the whole process of Gas making was not a chemical operation!

From this little incident it will be seen how intimately the various branches of my work ramified and interlaced.

It is a matter of frequent remark that the World is small.

I once had a curious instance of this when visiting the works at Crossness on one of my weekly inspections.  On turning the corner of one of the buildings I came on a medical man whom I had left at Clermont, in Queensland, some twelve years before.  He had come to England on a visit and had been instructed by the Queensland Government to make inquiries into sanitary matters and had called upon me in London and had followed me down to the Outfall by train.  Great was his surprised to find that the individual he was in search of was no other than the Clermont friend he had last seen “down under.”

When the London County Council succeeded the Metropolitan Board of Works in 1889 my work became very heavy, largely inconsequence of the retirement of the Engineer to the Board, Sir Joseph Bazalgette and the death of Mr Grant the Assistant Engineer for London “South of the Thames,” and the illness of Mr Lovick the Assistant Engineer in charge of London “North of the Thames.”  The first Chairman of the Main Drainage Committee appointed by the Council was Mr Rhodes who very properly “wanted to know” and began by asking me to prepare a report on the whole question of the Thames, in addition to weekly reports on the progress of the Engineering world!  This I accordingly did and prepared what came to be known in the Department as “Mr Dibdin’s Bible.”  At the request of the Committee this was prepared for printing but at the last moment they were frightened at the expense being at the time economically minded.  It took me two afternoons to go through the report with the Committee, one for the part relating the Deodorising operations and another for that relating to the purification work, so that the Committee had all the facts before them in detail, as I set out clearly and in sequence the whole story and left them with clear impression of the facts of the case.  It was no doubt due to this that the Council dispensed with the services of Sir Henry Roscoe, much to his indignations, and left me a clear field to carry on the policy which had been followed by the old Board, as the Council clearly saw that there was no practical alternative.  Mr Rhodes took great personal interest in the question and made repeated visits with me to the outfalls.  It was in connection with these that it wrote “I wish I could write a report of 38 pages on such a subject without a new word, a new thought or a new suggestion.”  PS  After “38 pages” and “two maps” . . . Tidy was a curious man.  I always said that if Tidy had been an actor Irvine would have had no chance.  He was very amusing at times.  I once met him at the Chemical Society and remarked that he was a little late – “Yes” he replied, “I was detained on an electric lighting case.  Never finish Electric Lighting cases.  No, not (in a whisper) Corporation cases either.”  That was in the good old days for Experts, when Pope and Bidder ruled the Parliamentary Bar and one could hardly move without running up against Frankland, Tidy, Bramwell or Mansergh to say nothing of Baldwin Latham and many others such as Hawksley, Sir Joseph Bazalgette, Reginald Ward & co.

ANNUAL INSPECTIONS OF THE ESTUARY

As it was proposed to discharge the sludge from the London sewage into the Estuary below the Nore it appeared to me only reasonable to ascertain before we commenced that work, the condition of the foreshores and sandbanks and on my suggestion an inspection was made in 1887.  One of the Sludge boars was put into commission for the work and accompanied by assistants with one of the Engineering staff to mark off the localities inspected and sites from which samples were to be collected and also one of Sir Henry Roscoe’s assistants.  I started for a ten days trip closely examining the foreshores from Purfleet to Harwich and from Margate back to Purfleet on the South side, also the sand banks which are exposed at low tide at the end of the Barrow Deep.  This was a pleasant break to the ordinary routine although it required close attention during working hours as I had taken my microscope on board and examined all the samples collected.

The inspection then became an annual one and thus any deterioration of the estuary would be detected at once.  During one of these inspections I made an estimate of the quantity of organic matter which would be in the water from the sewage on the assumption that none of it was destroyed during a year but was evenly distributed throughout the water of the estuary al all depths.  The quantity worked out to about one tenth of a grain per ton of water.  As, however, the destruction of the organic matter is extremely rapid by the action of the organism and the fish instead of its remaining unchanged for twelve months it is not surprising that we failed to detect any accumulation except one occasion when I detected a case of “dumping” as a result of my microscopical examinations.  The way of it was this.  Soon after we passed the Nore I found indications which were suspicious.  Further on all was clear again and nothing more was found until on our return journey we came to the sample . . .  I then had a chat with Captain Viveash, who was in charge and asked him how the tide generally set in the place.  On referring to the chart it was seen that about fifteen miles away the set of the tide was towards a submerged sandbank and it was evident that if anything would be found in the direction the edge of that particular bank would be affected.  We accordingly steamed to the spot and on dredging brought up a mass of decaying matter mixed with mud and sand.  The effect on the crew was very funny.  As soon as the dredger came up and was seen to be filled with the muck I suddenly found myself alone on the deck.  The Captain and Mate sheared off round the deck house and the crew found pressing work to do in other parts of the ship.  Then the story came out.  They knew perfectly well that some of the sludge boats had been making short trips and letting go their cargo too soon instead of over the ten mile course through the Barrow deep and Captain Viveash afterwards showed me a copy of a letter which he had written to one of the Captains calling his attention to the fact and warning him, Viveash being the Commodore of the fleet of six boats.  I have always thought that this instance of “steering the ship by the Microscope” was rather a feather in my cap as well as a good instance of what can be done by the use of this instrument.

EXPERIMENTS ON SEWAGE FILTRATION

THE ORIGIN OF THE CONTACT BEDS

In order to ascertain the possibility of further purifying effluent obtained from the treatment of the Sewage at the Outfalls experiments were made in 1892 with various filter beds which were constructed by Santo Crimp at that time Engineer for London North of the Thames under Mr Binnie.  As soon as they were ready and at work daily analyses were made by my staff at the Outfall Laboratory with the result of showing that the action of the beds was primarily mechanical followed by biological action on the matters collected in the filter and that the so called “Oxidation” by direct combination with the oxygen o the atmosphere or that in chemical combination with the filtering material was nonexistent.  The preliminary results from the small filters were so satisfactory that the Committee authorised the construction of one having an area of one acre.  When this was ready the engineers, against my advice insisted upon using it as an ordinary filter with the result that it became rapidly clogged and useless.  I then asked the permission of the Committee to make further experiments with it on Biological lines.  To this they consented and the first thing I did was to give it a three months rest to recuperate.  When the clinker was perfectly sweet showing that the anaerobic organisms had been replaced by the aerobic and that the organic matter with which it had been overcharged had been destroyed it was put to work with, at first, one filling of effluent from the precipitation tanks per day.  This was subsequently increased to two and then three fillings, with the result that the bed successfully purified one million gallons of the effluent daily, giving excellent results.  On one occasion when the Committee were making an inspection one of the members, Marlione Rolunson, said that “the man who did this ought to be made a prince.”

Being about that time concerned as a townsman in local affairs at Sutton, I recommended the Sutton Council to employ this method in place of the ordinary type of filters.  This they did with complete success.  I then recommended the Council to go one step further, viz; to fill one of the precipitation tanks with Coarse burnt ballast and turn the crude sewage into this on the assumption that just as the fine matters in the effluent settled in the interstices between the particles of fine material in the fine contact bed so the coarse particles would settle in the larger interactions between the larger particles in the primary beds and there become the food of various organisms.  This they did and so the “Course” Contact beds came into use at Sutton.

These were quickly copied throughout the Country especially at Manchester where the whole of the sewage of that City was treated by this method after long preliminary trials of various systems.  For years Sutton became the Mecca of the sewage world.

In1897 I read a further paper before the Institute of Civil Engineers on the results of the work on the Thames and gave the results of the filter experiments.  In the course of the discussion on the Paper I read in 1887 Mr Mansergh the well know engineer remarked “No doubt, to any one experienced in the chemical treatment of sewage, these figures of Mr Dibdin’s were startling figures, and if he proved, in actual working on a large scale at Barking, that he could produce a sufficiently good effluent with these quantities he would deserve infinite credit.”  In the second paper in 1897 I did so prove and the state of the River was and is my witness, for the scheme then foreshadowed is still at work.  In the discussion on the 1897 paper Mr Mansergh said that “he thought the Chemists had acted with sound judgement.”

In 1897 I published my work on “The Purification of sewage and Water” which was most favourably received and ran into three Editions.